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System design patterns

Sharding, load balancing, CAP tradeoffs, and scaling patterns — interview and production ready.

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How to implement saga orchestration with compensating steps in Python

Orchestrate a distributed transaction across services, rolling back completed steps with compensations when a later step fails.

saga distributed-transactions compensation

Python

class InventoryService:
    def reserve(self, order_id):
        print(f"[Inventory] Reserving stock for order {order_id}")
        return True

    def compensate(self, order_id):
        print(f"[Inventory] Releasing stock for order {order_id}")


class PaymentService:
    def charge(self, order_id):
        print(f…

15 0 Open

System design patterns medium

How to implement stale-while-revalidate caching in Python

A Python cache wrapper that returns a stale cached value with a fallback flag when the upstream fetch fails, using TTL-based freshness checks.

caching ttl resilience

Python

import time
from functools import lru_cache


class CachedService:
    def __init__(self, fetch_func, ttl=5):
        self.fetch_func = fetch_func
        self.ttl = ttl
        self._cache = {}
        self._timestamp = {}

    def get(self, key):
        now = time.time()
        if key in self._cache and now - self…

12 0 Open

System design patterns medium

Template Method Workflow Steps Base Class in Python

Define a reusable workflow skeleton in a base class and let subclasses fill in each step with the Template Method design pattern.

template-method design-patterns abc

Python

from abc import ABC, abstractmethod


class DataPipeline(ABC):
    """Template Method pattern: defines a workflow skeleton."""

    def run(self):
        """Template method - defines the algorithm's structure."""
        result = {"extracted": False, "transformed": False, "loaded": False}
        raw_data = self._ext…

13 0 Open

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